[Seaside] Catching Error in WAValidationDecoration

[C. David Shaffer]

I'm sure I don't need to expound upon problems with raising and catching 
generic errors.  Maybe WAValidationDecoration is just intended as an 
example of using a decoration but I'm afraid many people will use it and 
become frustrated.  I suggest the obvious: add a new exception class for 
validation errors and implement Object>>#validationError: to raise it.  
Sample code, though trivial, is attached.  Also, to attach the 
validation delegate you'll need to override validateWith: in your 
component class(es):

validateWith: aBlock
    self
        addDecoration: (SCValidationDecoration new validateWith: aBlock)

I'd be happy to rewrite this as a .cs which modifies the "WA" base 
classes and updates all of the existing examples...if there was a chance 
it would be changed in the base distribution.

David

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'From Squeak3.6 of ''6 October 2003'' [latest update: #5429] on 21 June 2004 at 12:02:23 pm'!
WADecoration subclass: #SCValidationDecoration
	instanceVariableNames: 'message validationBlock '
	classVariableNames: ''
	poolDictionaries: ''
	category: 'SC-Components'!

!SCValidationDecoration commentStamp: 'cds 5/31/2004 17:42' prior: 0!
I work just like a WAValidationDecoration except that I only catch instances of ValidationError.!

Notification subclass: #SCValidationNotification
	instanceVariableNames: ''
	classVariableNames: ''
	poolDictionaries: ''
	category: 'SC-Components'!

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 6/21/2004 11:58'!
handleAnswer: anObject 
	(super handleAnswer: anObject)
		ifFalse: [^ (self validate: anObject) not].
	^ true! !

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 5/31/2004 17:41'!
initialize
	message _ WAStateHolder new! !

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 5/31/2004 17:42'!
processRequest: aRequest do: aBlock 
	aBlock
		on: WAAnswerNotification
		do: [:n | (self validate: n value)
				ifTrue: [n pass]]! !

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 5/31/2004 17:42'!
renderContentOn: html 
	message contents
		ifNotNilDo: [:msg | html divClass: 'validation-error' with: msg].
	self renderOwnerOn: html! !

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 5/31/2004 17:44'!
validate: anObject 
	[validationBlock value: anObject.
	^ true]
		on: SCValidationNotification
		do: [:e | message contents: e messageText].
	^ false! !

!SCValidationDecoration methodsFor: 'as yet unclassified' stamp: 'cds 5/31/2004 17:42'!
validateWith: aBlock 
	validationBlock _ aBlock! !